Fuse



Patented Mar. 12, 1940 v UNITED STATES PATENT OFFICE FUSE Carl E. Mosley, Richmond Heights, Mo., minorto W. N. Matthews Corporation, St. Louis, Mo., a corporation of Missouri Application September 24, 1938, Serial No. 231,489 6 Claims. (01. 200-121 This invention relates to a fuse, and with regard pulsive action occurs, such constructions in any to certain more specific features, to a secondary event cause elongation between the separated or low-tension fuse. ends of the link leaders, thereby permitting the Amon the several objects of the invention may fuse as a whole to sag into a possibly dangerous be noted the provision of a fuse in which a fusible position. Furthermore, the constructions require I element, both before and after operation of the a more or less detailed examination to determine fuse, remains enclosed and which is provided with their blown condition.

indicating means whereby a blown condition may The present invention overcomes the above be recognized despite the enclosed condition; dlfliculties.

the provision of a fuse of the class described in Referring now more particularly to Fig. 1, there I. which the indicator is more reliable in operation are shown at numerals I and 3 flexible leaders and more distinctively visible than heretofore; composed of braided conducting wires, between the provision of apparatus of the class described w ch t e fu b e e e e t Tl s placed. which will not short-circuit under any conditions Surroundin the element 21 and inner ends of of operation; and the provision of apparatus of the leaders I, 3 is a tubular member 5, preferthis class which is simple and economical. Other ably mad n yc horn fi or he like. objects will be in part obvious and in part pointed Pressed with a relatively tig t fit Over lShe pp out hereinafter. end of the tube 5 is a metallic conducting cap 1 The invention accordingly comprises the eleirom the end of which extends a nipple 9- The 0 ments and combinations of elements, features of n pp e 9 is e mp d o tight pp contact Q construction, and arrangements of parts which with the leader I, as indicated at ll.

will be exemplified in the structures hereinafter At the lower end of the tube 5. is a second I described, and the scope of the application of Cap I which is tightly forced on the tube 5 and which will be indicated in the following claims. which has a nipp The nipple I3 is ped In the accompanying drawing in which is 11- tightly to grip the leader 3, as indicated at is. iustrated one of various possible embodiments The caps I and I! are Prevented from rotating of the invention, or moving endwise with respect to the tube 5 by Fig, 1 is a side elevation of a fus embodying means of set screws I9 and 2| respectively. It the invention, showing the parts in unblown conwill be understood that other forms Of old dition; I means may be used, such as screw caps, notched 80, Fig. 2 is a vertical section taken on line 22 ea s o th like- Th importance 1 the holdof Fig. 1; and, ing means I9, 2| for the caps l, I I is that there- Flg. 3 is a front elevation wh r in th parts by relative rotation between the leaders I and 3 are shown in blown and indicating position. is prevented, the leaders being held (crimped) to 36 Similar reference characters indicate corre- D ts attached o the p I ll sponding parts throughout the several views of It wi be de s o d t a the pp 9 d the drawing. v I3 may be integral with the caps 'I and II re It is desirable on a secondary fuse to have an spectively, a sh w r t a th y ma be separate indication of any fused condition. Some soluut fast d, as by s d r or-the k The 40 tions to a problem of providing an indicator have container ed y parts 3, I5 and 40 resulted in constructions wherein the enclosures n s -D Q have been arranged to be only partially sealed, About the inner ends of the leaders I and 3, by reason of the requirement for an endwise proo lars 3 a d 15 e p c y are p 9 iection from the enclosure of an indicator means, hold in position the fusible element 21. Before such as a spring. Such a construction does not crimping, the ends ofthe fusible elements are 4| permit of sealing the enclosure as tightly as vis thrust in next to the strands of the leaders I and desirable, with the result that water may enter 3, thus making an efficient electrical connection. and interiorly swell the fibre of the enclosure, The fusible element 21 is prefe made of and hence impair its reliability of operation. Furelatively heavy c pp the likethermore, such constructions, by reason of the ex- Outside of the tube 5 is arranged a shunt wire so pulsive action which occurs by reason of the 29, preferably of relatively small, cross section loose-end construction, sometimes cause the fuse and composed of stainless steel or the like. This leader ends to separate entirely so that dangling wire is held at its upper ends in electrical conportions become dangerous in forming short cirnection with the cap I, as by means of the set 5 ouits with surrounding wires. Even when no exscrew I9 and extends downwardly'to malreelecl5 trical contact with thenipple l3 as by means of solder 3|.

The shunt wire 29 passes through an outwardly located tube 33, preferably formed of Bakelite,

fibre or the like and through a spring 35. The

spring 35 is also held in position at its lower end as by means of the solder 3| and at its other end is threaded into the tube 33 to support the tube- As shown in Figs. 1 and 2, the shunt wire 29 is arranged parallel to the tube or case 5 so that the spring 35 is flexed and the indicator tube is held in a position parallel to and against the tube 5.

Operation of the device is as follows, assuming that the leaders I and 3 are fastened into a suitable low-tension electrical circuit, preferablya secondary circuit:

The fusible conducting element 21 normally carries the major portion of the current until the current increases to a point where this element melts. Instantly the full current passes through the stainless steel shunt wire 29, which melts and releases the tell-tale or indicator tube 33. Under the straightening action of released spring 35, this tube 33 rises to a position perpendicular to the tube 5, as indicated in Fig. 3. The right-angular relationship between the tubes 33 and 5, after blowing, as compared with the parallel relationship before blowing, provides a definite indication of the fused condition of the device.

Ordinary action will not move either of the caps I or H from the tube. Thus, the distance between the caps remains constant and the assembly of leaders I and 3 with the tube 5 is as short after blowing as before. Therefore the device does not sag between the circuit contacts which hold it, nor will any loose wires dangle.

Furthermore, since the caps I and H have no relative motion with respect to the tube 5, they can be made with the desired tight fit, so that, taken in connection with the squeezing necessary to make the crimps l5 and H, the inside of the tube 5 is substantially protected against inward leakage of water. The inability ofthe caps 1 and II to rotaterelatively prevents inadvertent twisting of the fusible element 21.

It is to be understood that the actual diameters of wire 21 and wire 29 are selected so that fusion of wire 21 takes place under the desired electrical conditions, and so that thefusion of wire 29 takes place after the fusion of wire 21. In order to accomplish this end, wire 21 will ordinarily be larger than'wire 29, although not necessarily so.

It is also to be understood that the device is useful when the shunt wire 29 fuses at the same time that the fusible element melts, or even when the wire 29 fuses ahead of the fusible element 21. It is only necessary that the fusion of wire 21 be insured when the signal indicates such a condition. In practice, so far as the ordinary observer is concerned, the signal means will be set to indicate a fused condition substantially at the time that the fusible element 21 melts. 4

If desirable, the outside of the tubes 5 and 33 may be made luminescent by suitable means, such as by applying a luminescent paint. This would provide an indication at night of the relative positions of the tubes. Or, merely the tube 33 may be made luminescent, in cases where its .absolute position has meaning to an inspector.

It is to be understood that, although the tube 5 is interiorly composed of horn fiber or the like, it may be made up with an exterior surface of Bakelite or the like, or it may be made of other suitable material. The material of which the tube 33 is made may also have mechanical equivalents.

In view of the'above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from thescope of -means externally of said container, a shunt conductor externally of said container and electrically shunting the fusible element, said shunt conductor being adapted to fuse substantially when the fusible element fuses, and biased signalling means held by the shunt means in one position under unfused conditions of the shunt means, and movable to a second position under fused conditions of the shunt means.

2. A fuse comprising a pair of spaced, flexible leaders, a fusible element joining said leaders, a non-conducting, weather-proof and complete enclosure about said fusible element and joined to said leaders in a weather-proof manner and permanently to hold them at a predetermined spacing, signal means externally of said container, a shunt conductor externally of said container and electrically shunting the fusible element, said conductor being adapted to fuse substantially when the fusible element fuses, and biased signalling means held in one position under unfused conditions of the shunt, whereby it moves to a second position under fused conditions of the shunt conductor.

3. A fuse comprising a pair of leaders, fusible means connecting said leaders, a tubular container surrounding said fusible element and at tached to. the-leaders, said container being nonconducting between the leaders, a tubular signalling element externally of the container having a position parallel to and adjacent the container and a second position at an angle thereto, a coil spring fastened to the signalling element and biasing the signalling element from its parallel to its angular position, and a shunt wire electrically connected between said leaders and threading the tubular signalling element.

' 4. A fuse comprising a pair of leaders, fusible means connecting said leaders, a tubular container surrounding said fusible element and. attached to the leaders, said container being nonconducting between the leaders, a tubular signal element externally of the container and having aposition parallel to and adjacent the container and a second position at an angle thereto, a coil spring fastened to the signal element and biasing the signalling element from its parallel to its angular position, and a shunt element threading the tubular signal element and when unfused biasing the signal element to its parallel position and when fused releasing the signal element to assume an angular position.

5. A fuse comprising a pair of conducting leaders, a conducting fusible element between the leaders, an enclosing insulating tube surrounding said fusible element, conducting caps tightly and amaaoa ing tube and a second one at an angle thereto, a coil spring attached to the signal tube at one end and made fast to a stationary part at the other end, and a, shunt wire electrically connected between the leaders and threading the signal tube and said spring.

6. A fuse comprising a pair of conducting leaders, a conducting fusible element between the leaders, collars crimped about the ends of the leaders and fusible element to connect them electrically, an enclosing insulating tube surrounding said fusible element, conducting caps tightly and non-rotatably'fltted to said tube, parts non-rotatably associated with said caps and tightly crimped to said leaders, a tubular signal outside of said tube and having a first position parallel to the enclosing tube and a second one at an angle thereto, a coil spring attached to the signal tube at one end and made fast to a stationary part at the other end, and a shunt wire electrically connected between' the leaders and threading the signal tube and said spring.

CARL E. MOSLEY. 

